Abstract

Rabbit bronchus associated lymphoid tissue (BALT) (1) and Peyer’s patches (2,3) contain cells which recognize locally presented antigen, and which respond by cell division. These observations are consistent with an emerging concept that aggregated mucosal lymphoid structures “sense” lumenal antigen, and amplify the local immune response. However antigen-induced cell proliferation in vitro occurs under restricted conditions and the rate of DNA synthesis is less than that observed for circulating cells following systemic immunization (1,3). The reason(s) for this difference between mucosal and circulating lymphocytes is not clear, but the demonstration of a suppressor cell population within the mouse Peyer’s patch, suggests that cell-dependent regulation may limit the local inflammatory response to environmental antigen.